Welding station framing apparatus with breakaway provision

ABSTRACT

A motor vehicle car body framing apparatus for use at a welding station, the apparatus including a gate having a frame structure and a plurality of tooling members carried by the frame structure for use in positioning components of the vehicle body at the welding station for welding. The tooling members are mounted on the frame structure by a plurality of mounting brackets. Each mounting bracket includes a base member mounted on the frame structure and a riser mounted on the base and mounting a respective tooling member. The riser is fixedly mounted on the base by a single central fastener bolt which may include a reduced diameter portion sized to break away in response to predetermined impact against the riser. Each mounting bracket further includes means defining a triangulated mounting interface between the base and the riser arranged in concentric relation to the fastener bolt. The triangulated mounting interface may comprise a raised ring surface on one of the base and the riser centered on the axis of the fastener bolt and positioned at the mounting interface of the base and the riser. Each mounting bracket further includes two dowels received in aligned apertures in the base and in the riser at locations flanking the axis of the fastener bolt.

RELATED APPLICATION

This application claims the priority of U.S. Provisional PatentApplication 60/675,222, filed on Apr. 27, 2005.

FIELD OF THE INVENTION

This invention relates to a production line framing apparatus forclamping and thereafter welding a loosely assembled vehicle body andmore particularly to a framing apparatus that accurately positions andlocates predetermined areas of a loosely assembled vehicle body at awelding station for accurately clamping and welding the vehicle bodytogether with a high degree of repeatability between consecutive vehiclebodies on the production line

BACKGROUND OF THE INVENTION

The construction of a unitized vehicle body commences with the formationof individual major body panels by stamping the panels from sheet metalblanks. Typically these major panels include a floor panel, right andleft body side panels, a fire wall and either a roof panel ortransversely extending header members to which a roof panel issubsequently mounted. After the individual panels are stamped, somepreliminary assembly operations may then be performed on the individualpanels such as, for example, adding door hinge and latch hardware at thebody side panels at appropriate locations proximate the door opening,adding seat mounting brackets, adding reinforcements to the body panel,etc.

Next a set of panels that together constitute a sub-assembly of thefinished vehicle body is loosely assembled together. This initial looseassembly of panels frequently is accomplished by a “toy tab” arrangementin which one or more panels is formed with a tab which projects from anedge and which is received in a slot in an adjacent panel. Thistechnique interlocks the panels and frame members to each other tothereby form a preliminary loosely assembled vehicle body wherein thepanels and frame members will not separate from each other but whereinthe panels and frame members are free to tilt or otherwise move relativeto one another. This initial loosely-assembled subassembly is thenbrought, as for example by a pallet riding on rails, to a weldingstation where the various panels and frames are welded to each other ina rigid permanently assembled relationship. This initial weldingoperation step at the welding station is one of the most important stepsin the assembly of the vehicle body because it establishes the finalwelding alignment of all of the various panels and headers relative toeach other which is essential to subsequent assembly operationsperformed on the sub-assembly. During the welding operation it isdesirable that the various panels and headers be precisely andaccurately located and aligned relative to one another and be heldfixedly in the desired position. The positioning of the various panelsand header members during the welding operation at the welding stationis accomplished utilizing a framing apparatus located at the weldingstation and including a plurality of gates. For example, a pair of sidegates may be utilized in combination with a top gate with the gatesmoveable between retracted positions, to allow the entry of the vehicleassembly into the welding station, and working positions wherein toolingmembers carried by the gates suitably engage the assembled body panelsto fix them into desired finalized positions whereafter programmablewelding robots, each provided with a welding gun, perform weldingoperations on the assembled body components as they are held in place bythe gates and the tooling members.

Prior art welding gates tend to be rather bulky and heavy apparatusesdue to the necessity of carrying many and sometimes rather complicatedand heavy tooling members and this heavy construction of the gates hasnecessitated cumbersome and expensive power equipment to move the gatesbetween their retracted and working positions. The bulky and heavyconstruction of the welding gates has also interfered with the abilityof the robots to access the vehicle body components located within thegates.

In an attempt to reduce the bulk and weight of the gates, gates havingan open frame or skeletal structure have been utilized but these openframe structure gates, by their fragile nature, have difficulty inhandling all of the heavy tooling members and are subject to damage as aresult of inadvertent impact with obstacles. Such impacts may not onlydamage the gate but may also misalign tooling members carried by thegate with resultant imprecise joinder of the various body panels.

SUMMARY OF THE INVENTION

This invention is directed to the provision of an improved framingapparatus for use at a car body welding station.

More particularly, this invention is directed to the provision of aframing apparatus utilizing a relatively light weight gate that is yetcapable of handling even very heavy tooling members.

Yet more particularly, this invention is directed to the provision of aframing apparatus with breakaway provisions to preclude damage to thegate and/or the tooling members in the event of inadvertent encounterswith obstacles.

The motor vehicle car body framing apparatus of the invention isintended for use at a welding station and includes a plurality oftooling members for use in positioning components of the vehicle body atthe welding station for welding, the tooling members being mounted onthe framing apparatus by a plurality of mounting brackets.

According to the invention, each mounting bracket includes a base membermounted on the framing apparatus and a riser mounted on the base andmounting a respective tooling member; the riser is fixedly mounted onthe base by a single central fastener bolt; and the fastener boltincludes a reduced diameter portion sized to break away in response topredetermined impact against the riser.

According to a further feature of the invention, the fastener boltpasses through an unthreaded central aperture in the riser for threadedengagement with a threaded central aperture in the base.

According to a further feature of the invention, the fastener boltincludes a head portion and a shank portion and the shank portiondefines the reduced diameter portion.

According to a further feature of the invention, the head portion alsoincludes a reduced diameter portion and the reduced diameter portion ofthe head portion is designed to shear before the reduced diameterportion of the shank portion so that the tightening of the fastener boltuntil the reduced diameter head portion shears has the effect ofpre-torqueing the fastener bolt to the torque level required to shearthe reduced diameter head portion.

According to a further feature of the invention, each mounting bracketfurther includes at least one dowel received in aligned apertures in thebase and in the riser at a location offset from the axis of the fastenerbolt.

According to a further feature of the invention, each mounting bracketincludes two dowels received in aligned apertures in the base and in theriser at locations flanking the axis of the fastener bolt.

According to a further feature of the invention, each base includes aplanar platform portion mounting the respective riser and a plurality oflegs extending from the platform portion and sized to straddle the framestructure.

According to a further feature of the invention; each riser is mountedon the base by a single central fastener bolt and the interface betweenthe riser and the base comprises a plurality of contact points arrangedin concentric relation with respect to the fastener bolt.

According to a further feature of the invention, the contact points atthe interface between the riser and the base define a triangulatedmounting interface.

According to a further feature of the invention, the means defining thetriangulated mounting interface comprises a raised ring surface on oneof the base and the riser centered on the axis of the fastener bolt andpositioned at the mounting interface of the base and the riser.

In one embodiment of the invention, the raised ring surface is definedon the base and a series of lugs are defined on the inner periphery ofthe ring surface with each lug defining an aperture for receipt of adowel.

In another embodiment of the invention, the raised ring surface isdefined on the riser and the raised ring surface as received in a socketformed in a confronting face of the base.

The invention also sets forth similar features relating to the mountingbracket per se and to the methodology employed in mounting the mountingbracket on the framing apparatus.

Other applications of the present invention will become apparent tothose skilled in the art when the following description of the best modecontemplated for practicing the invention is read in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and wherein:

FIG. 1 is a schematic view of a motor vehicle framing production lineincluding a framing station;

FIG. 2 is a schematic cross-sectional view of the framing station;

FIG. 3 is a side elevational view of a gate utilized at the framingstation;

FIG. 4 is a perspective view of the gate viewed from below the gate;

FIG. 5 is a perspective view showing a gate in conjunction with a robotutilized to position the gate;

FIG. 6 is a exploded perspective view of a mounting bracket for use inmounting tooling members on the gate;

FIG. 6 a shows a detail of FIG. 6;

FIG. 7 is a cross-sectional view of the mounting bracket;

FIG. 7 a shows a detail of FIG. 7;

FIG. 8 is a detail view of a bolt structure utilized in the mountingbracket;

FIG. 9 illustrates a mounting bracket mounted on a gate;

FIG. 10 illustrates a break away feature of the mounting bracket; and

FIGS. 11, 12 and 13 illustrate an alternate mounting bracket structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1 an initial loosely assembled body subassemblyseen generally at 10 is brought, as for example by a pallet 12 riding onrails 14, to a welding station 16 where the various panels and framesare welded to each other in a rigid permanently assembled relationship.The positioning of the various panels and header members during thewelding operation at the welding station is accomplished utilizing aframing apparatus 15 including a plurality of gates. For example, asseen schematically in FIG. 1, a pair of side gates 18 and 20 may beutilized in combination with a top gate 22 with the gates moveablebetween retracted positions seen in FIG. 1, to allow the entry of thevehicle assembly 10 into the welding station, and working positions seenin FIG. 2, wherein tooling members carried by the gate suitably engagethe assembled body panels to fix them into desired finalized positionswhereafter programmable welding robots 26, each provided with a weldinggun 28, perform welding operations on the assembled body components asthey are held in place by the gates 18, 20 and 22 and the toolingmembers 24.

The framing apparatus of the invention uses an open frame gate structure30 (FIGS. 3-4) in combination with a plurality of mounting bracketstructures 32 to facilitate attachment of the tooling members to thegate. Gate 30, which may comprise either a top gate or a side gate, hasan open frame skeletal structure comprising skeletal, parallel,longitudinal side members 34, skeletal end cross-members 36, skeletalimmediate cross-members 38, a central robot mounting plate 40, skeletalupper parallel side rails 42, skeletal upper cross-members 44, andlattice members 46 interconnecting each upper side rail to therespective lower rail. All of the members of the frame are preferablyformed of a lightweight tubular material of rectangular cross-sectionhaving a wall thickness of, for example, 60 thousandths of an inch andall of the members are formed of a suitable ferrous material. The framecomponents are secured together by welding utilizing suitable gussets48.

Each mounting bracket structure 32 (FIGS. 6 and 7) includes a base 50, ariser 52, and a bolt structure 54.

Base 50 may be formed as a cast ferrous structure and includes a planarplatform portion 50 a and a plurality of legs 50 b integrally upstandingor downstanding from the platform portion. Platform portion 50 a mayhave a generally rectangular or hexagonal configuration and legs 50 bare positioned on the corners of the platform portion. Each leg 50 b(FIG. 6 a) had a right angle cross-sectional configuration and theplatform portions and legs are configured and dimensioned such that thebase 50 may be positioned over a skeletal frame member such for exampleas frame member 34 as best seen in FIG. 6. As shown, platform portion 50a may have a rectangular as opposed to a square configuration so thatthe legs 50 b on the long sides of the rectangle are spaced apartfurther than the legs 50 b on the short side of the rectangle so thatthe base may be positioned over the narrow top of a skeletal member 34as seen on the left side of FIG. 6 or over the wider side of the member34 as seen on the right side of FIG. 6 so that the base has universalapplication with respect to the skeletal members of the frame structure30.

The platform portion 50 a of each base defines a planar platform surface50 c removed from the side 50 d from which the legs extend. A centralthreaded aperture 50 e is provided in the platform portion proximate thegeometric center of the platform portion and opening in the platformsurface 50 c, and a raised ring 50 k is provided on the platform surface50 c centered on the threaded aperture 50 e. A series of lugs 50 f areprovided on the inner periphery of ring 50 k and each defines a centralaperture 50 g.

Each riser 54 includes a riser portion 52 a, a horizontal portion 52 band a gusset portion 52 c interconnecting the riser portion and thehorizontal portion. A central unthreaded aperture 52 d is provided inhorizontal portion 52 b proximate the geometric center of the horizontalportion 52 b and a pair of further apertures 52 e are provided inhorizontal portion 52 b in flanking relation to central bore 52 d.

Bolt structure 54 (FIGS. 6, 7, 7 a and 8) includes a hexagonal headportion 54 a including a reduced diameter portion 54 b, a flange portion54 c, and a shank portion 54 d including a smooth shank portion 54 e, areduced diameter breakaway portion 54 f, and a threaded shank portion 54g.

It will be understood that a bracket structure 32 is positioned on oneof the skeletal members of the frame structure at any location along theframe structure wherein it is desired to position a tooling member 24 toengage a body component. The tooling member 24, which may typicallycomprise a clamp, is seen schematically in FIGS. 7 and 9.

In use, a base member 50 is positioned over a skeletal member of theframe with the legs in straddling relation to the skeletal member andthe face 50 d of the platform portion positioned against the skeletalmember whereafter the base is welded to the frame member over the entireU-shaped interfaces between the base and the frame member as defined bythe coacting of legs 50 b and face 50 d.

Following welding of the base member 50 to the skeletal members of theframe, a pair of dowels or pins 60 are positioned in diametricallyopposed apertures 50 g in the platform portion; a riser 52 is positionedover the platform portion to pass the exposed ends of the dowels intothe apertures 52 e and align the unthreaded central riser aperture 52 dwith the threaded central base aperture 50 e with the horizontal portion52 b seated against the ring 50 e; a bolt structure 54 is passeddownwardly through aperture 52 d to threadably engage bolt threadedshank portion 54 g in threaded bore 52 e of the base platform portion;the bolt is tightened utilizing head 54 a until the flange portion 54 cseats against the upper face of horizontal portion 52 b; and furthertorque is applied to the bolt via the head 54 a until the reduceddiameter portion 54 b shears, as seen in FIG. 9. It will be understoodthat reduced diameter portion 54 b is designed to shear before reduceddiameter portion 54 f and that the tightening of the bolt structureuntil the reduced diameter portion 54 b shears has the effect ofpre-torqueing the bolt to the torque level required to shear the reduceddiameter portion 54 b.

In use at the framing station, each open frame gate structure 30 ispositioned by a robot 62 which is secured to robot mounting plate 40 andprogrammed in known manner. Ideally, the robot moves the gate intoposition at the framing station without encountering any obstacles andtherefore without damaging the tooling members or, more importantly, thedelicate frame structure. However, if an obstacle is encountered, theobstacle will typically exert a force F (FIG. 10) against the verticalportion 52 a of a riser which in turn will cause the riser to tilt abouta fulcrum defined by a point on the ring 50 k which in turn will resultin shearing or rupture of the reduced diameter bolt portion 54 f whichin turn will allow the riser and associated tooling member to break awayfrom the base 50 and preclude twisting or other damage to the delicateframe structure 30 and/or dislocation of the tooling member carried bythe riser portion and consequent mis-assembly of the respectiveautomotive body components. The ring 50 k has the effect of defining afulcrum comprised of a locus of interface points concentrically equaldistant from the central bore 50 e so that no matter in which directionthe impact F is exerted on the riser portion 52 a the same moment willbe applied to the riser and to the bolt structure and the same forcewill result in an identical rupture pattern with respect to the reduceddiameter bolt structure portion 54 f. Since the interface between theriser and the base is only along the well defined ring surface 50 k, thering surface 50 k also has the effect of insuring that the riser willengage the base at a plurality of contact points at the interfacebetween the riser and the base arranged in concentric relation withrespect to the fastener bolt and, specifically, insures that the riserengages the bolt in a triangulated manner to provide a firm positiveinter-engagement between the riser and the base.

The dowels 60 function to preclude lateral or sliding movement of theriser on the base whereby to assure a uniform moment arm for the load asdefined by the locus point on the ring 50 k, irrespective of theobstacle angle of attack or point of attack.

In the alternate bracket structure seen in FIGS. 11-13, the underside ofeach horizontal portion 52 b of each riser includes a ring structure 52f centered on the central aperture 52 d, and defining a circular ringsurface 52 g centered on aperture 52 d. Ring structure 52 f is sized toseat within a circular socket 50 h formed in the upper face 50 c of theplatform portion of the base 50. In this case, a force F applied to thevertical portion 52 a of a riser results in tilting of the horizontalportion 52 b of the riser about a fulcrum defined by a point on the ring52 f. This arrangement, as with the FIGS. 1-13 embodiment, insures thatthe same moment loading will be applied to the bolt structure, andparticularly to the reduced diameter portion 54 f of the bolt structure,irrespective of the direction of impact of an obstacle against thevertical portion of the riser and further insures a firm positivetriangulated interface engagement of the riser on the base. In this casea dowel is not necessary to preclude sliding of the riser relative tothe base but a dowel 62 is nevertheless employed, received in apertures52 e and 50 g, to assist in orientation of the riser relative to thebase.

It will be seen that, either with respect to the bracket structure seenin FIGS. 1-12 or the structure seen in FIGS. 11-13, the bolt structure54 will shear at the reduced diameter portion 54 f before anysignificant twisting or other damage can be sustained by the delicateframe structure. It will be further seen that, in either construction,the concentric arrangement of the ring 50 k or the ring 52 f insuresthat the bolt structure will shear under the same impact irrespective ofthe direction of the impact force imposed by the encountered obstacle.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures as is permitted under the law. For example, although theinvention has been described with respect to a motor vehicle total carbody framing apparatus, it will be understood that the invention is alsoapplicable to partial body or component motor vehicle framing apparatusand is also applicable to the assembly of aircraft bodies or other bodystructures.

1. A body framing apparatus for use at a welding station, the apparatusincluding a plurality of tooling members for use in positioningcomponents of the body at the welding station for welding, the toolingmembers being mounted by a plurality of mounting brackets, characterizedin that: each mounting bracket includes a base for mounting on theframing apparatus and a riser mounted on the base and mounting arespective tooling member; the riser is fixedly mounted on the base by asingle central fastener bolt; and the fastener bolt includes a reduceddiameter portion sized to break away in response to predetermined impactagainst the riser.
 2. A framing apparatus according to claim 1 whereinthe fastener bolt passes through an unthreaded central aperture in theriser positioned proximate the geometric center of the riser forthreaded engagement with a threaded central aperture in the basepositioned proximate the geometric center of the base.
 3. A framingapparatus according to claim 2 wherein: the fastener bolt includes ahead portion and a shank portion; and the shank portion defines thereduced diameter portion.
 4. A framing apparatus according to claim 3wherein: the head portion also includes a reduced diameter portion; andthe reduced diameter portion of the head portion is designed to shearbefore the reduced diameter portion of the shank portion so thattightening of the fastener bolt until the reduced diameter head portionshears has the effect of pre torqueing the fastener bolt to the torquelevel required to shear the reduced diameter head portion.
 5. A framingapparatus according to claim 1 wherein each mounting bracket furtherincludes at least one dowel received in aligned apertures in the baseand in the riser at a location offset from the axis of the fastenerbolt.
 6. A framing apparatus according to claim 5 wherein each mountingbracket includes two dowels received in aligned apertures in the baseand in the riser at locations flanking the axis of the fastener bolt. 7.A framing apparatus according to claim 1 wherein each base includes aplanar platform portion mounting the respective riser and a plurality oflegs extending from the platform portion and sized to straddle the framestructure.
 8. A framing apparatus according to claim 1 wherein eachmounting bracket further includes means defining a triangulated mountinginterface between the base and the riser.
 9. A framing apparatusaccording to claim 8 wherein the means defining the triangulatedmounting interface comprises a raised ring surface on one of the baseand the riser centered on the axis of the fastener bolt and positionedat the mounting interface of the base and the riser.
 10. A framingapparatus according to claim 9 wherein the raised ring is defined on thebase.
 11. A framing apparatus according to claim 10 wherein: a series oflugs are defined on the inner periphery of the ring surface; and eachlug defines an aperture for receipt of a dowel.
 12. A framing apparatusaccording to claim 10 wherein the raised ring is defined on the riser.13. A framing apparatus according to claim 12 wherein the raised ringsurface is received in a socket formed in a confronting face of thebase.
 14. A body framing apparatus for use at a welding station, theapparatus including a plurality of tooling members for use inpositioning components of the body at the welding station for welding,the tooling members being mounted by a plurality of mounting brackets,characterized in that: each mounting bracket includes a base formounting on the framing apparatus and a riser mounted on the base andmounting a respective tooling member; the riser is mounted on the baseby a single central fastener bolt; and the interface between the riserand the base comprises a plurality of contact points arranged inconcentric relation with respect to the fastener bolt.
 15. A bodyframing apparatus according to claim 14 wherein the fastener boltincludes a reduced diameter portion sized to break away in response topredetermined impact against the riser.
 16. A mounting bracket for usein a body framing apparatus located at a welding station, the framingapparatus including a plurality of tooling members for use inpositioning components of the body at the welding station for welding,each tooling member mounted on the framing apparatus by a mountingbracket, characterized in that: each mounting bracket includes a basefor mounting on the framing apparatus, a riser mounted on the base andmounting a respective tooling member, and a single central fastener boltoperative to fixedly mount the riser on the base; and the fastener boltincludes a reduced diameter portion sized to break away in response to apredetermined impact against the riser.
 17. A mounting bracket accordingto claim 16 wherein each fastener bolt passes through an unthreadedcentral aperture in the respective riser position proximate thegeometric center of the riser for threaded engagement with a threadedcentral aperture in the respective base positioned proximate thegeometric center of the base.
 18. A mounting bracket according to claim17 wherein: each fastener bolt includes a head portion and a shankportion; and the shank portion defines the reduced diameter portion. 19.A mounting bracket according to claim 18 wherein: the head portion alsoincludes a reduced diameter portion; and the reduced diameter portion ofthe head portion is designed to shear before the reduced diameterportion of the shank portion so that tightening of the fastener boltuntil the reduced diameter head portion shears has the effect of pretorqueing the fastener bolt to the torque level required to shear thereduced diameter head portion.
 20. A mounting bracket according to claim16 wherein each mounting bracket further includes at least one dowelreceived in aligned apertures in the base and in the riser at a locationoffset from the access of the fastener bolt.
 21. A mounting bracketaccording to claim 20 wherein each mounting bracket includes two dowelsreceived in aligned apertures in the base and in the riser at locationsflanking the axis of the fastener bolt.
 22. A mounting bracket accordingto claim 16 wherein each base includes a planar platform portionmounting the respective riser and a plurality of legs extending from theplatform portion and sized to straddle the framing apparatus.
 23. Amounting bracket according to claim 16 wherein each mounting bracketfurther includes means defining a triangulated mounted interface betweenthe base and the riser.
 24. A mounting bracket according to claim 23wherein the means defining the triangulated mounting interface comprisesa raised ring surface on one of the base and the riser centered on theaccess of the fastener bolt and positioned at the mounting interface ofthe base and the riser.
 25. A mounting bracket according to claim 24wherein the raised ring is defined on the riser.
 26. A mounting bracketaccording to claim 25 wherein: a series of lugs are defined on the innerperiphery of the ring; and each lug defines an aperture for receipt of adowel.
 27. A mounting bracket according to claim 25 wherein the raisedring is defined on the riser.
 28. A mounting bracket according to claim27 wherein the raised ring surface is received in a socket formed in aconfronting face of the base.
 29. A mounting bracket for use in a bodyframing apparatus located at a welding station, the framing apparatusincluding a plurality of tooling members for use in positioningcomponents of the body at the welding station for welding, each toolingmember mounted on the framing apparatus by a mounting bracket,characterized in that: each mounting bracket includes a base formounting on the framing apparatus and a riser mounted on the base andmounting a respective tooling member; the riser is mounted on the baseby a single central fastener bolt; and the interface between the riserand the base comprises a plurality of contact points arranged inconcentric relation with respect to the fastener bolt.
 30. A mountingbracket according to claim 29 wherein the fastener bolt includes areduced diameter portion sized to break away in response to apredetermined impact against the riser.
 31. For use with a body framingapparatus including a plurality of tooling members for use inpositioning components of the body at a welding station for welding, amethod of mounting the tooling members on the framing apparatuscomprising: providing a plurality of mounting brackets, each including abase and a riser mounting a respective tooling member; fixedly mountingthe base on the framing apparatus; and fixedly mounting the riser onbase utilizing a single central fastener bolt having a reduced diameterportion sized to breakaway in response to a predetermined impact againstthe riser.
 32. A method according to claim 31 including the further stepof providing a triangulated mounting interface between the riser and thebase in concentric surrounding relation to the fastener bolt axis.
 33. Amethod according to claim 32 wherein the step of providing atriangulated mounting interface between the riser and the base comprisesproviding a raised ring on one of the base and riser centered on thefastener bolt axis.
 34. A method according to claim 33 wherein: thefastener bolt includes a head portion and a shank portion; the reduceddiameter portion is provided in the shank portion; and the methodincludes the further step of providing a further reduced diameterportion in the head portion sized to shear before the reduced diameterportion of the shank portion so that tightening of the fastener boltuntil the reduced diameter head portion shears has the effect ofpre-torqueing the fastener belt to the torque level required to shearthe reduced diameter head portion.
 35. A method according to claim 31including the further steps of: providing an unthreaded central aperturein the riser positioned proximate the geometric center of the riser;providing a threaded central aperture in the base positioned proximatethe geometric center of the base; providing a dowel aperture in theriser offset from the central riser aperture; providing a dowel aperturein the base offset from the central base aperture; positioning a dowelin one of the dowel apertures; positioning the dowel in the other dowelaperture; and passing the fastener bolt through the unthreaded centralriser aperture for threaded engagement with the threaded central baseaperture with the reduced diameter portion positioned proximate theinterface between the 4riser and the base.
 36. A method according toclaim 35 wherein each mounting bracket includes two dowels received inaligned apertures in the base and in the riser at locations flanking theaxis of the fastener bolt.
 37. For use with a body framing apparatusincluding a plurality of tooling members for use in positioningcomponents of the body at a welding station for welding, a method ofmounting the tooling members on the framing apparatus comprising:providing a plurality of mounting brackets, each including a base and ariser mounting a respective tooling member; fixedly mounting the base onthe framing apparatus; and fixedly mounting the riser on the baseutilizing a single central fastener bolt and a plurality of contactpoints at the interface between the riser and the base arranged inconcentric relation with respect to the fastener bolt.
 38. A methodaccording to claim 37 wherein the fastener bolt has a reduced diameterportion sized to break away in response to a predetermined impactagainst the riser.